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Environmental fate & pathways

Phototransformation in air

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Description of key information

The tropospheric half-lives of the cresol isomers (o-, m-, and p-cresol) range between 3.8 and 9 hours.

Key value for chemical safety assessment

Additional information

o-cresol

In the atmosphere, o-cresol will react with photochemically produced hydroxyl-radicals. In his critical review Atkinson (1994) recommended values for the reaction constant kOH at room temperature of 4.2 x 10-11 cm3 x molecule-per second. Based on a tropospheric OH radical concentration of 5 x 105 molecules per cm3 a corresponding half-life of 9.0 h can be calculated.

m-cresol and p-cresol

The tropospheric half-life of the cresols due to degradation by OH radicals with an average concentration of 500000 radicals/mL is approximately 6 h for m-cresol (Atkinson 1994) and 8 h for p-cresol (Atkinson 1989, 1994). An even shorter half-life of 3.8 h at ambient temperature is calculated for m-cresol and p-cresol from smoke chamber experiments at different temperatures (Semadeni et al. 1995).